Probably this race idea will not be realised soon.
We need to balance and add more content to dwarves, add scaledfolk, add some more content to other races.

Another problem - summoning structures as you described. It is not yet in the game and will take time to implement.

And with each additional race included it will be such a pain to balance.
For example scaledfolk will have more poison variants - dots, fire-based ones, slowing... Must be this race be immune to all of these variants? If yes than scaledfolk will be powerless to it.
Dwarves and orcs will be such a pain for this race to deal with.
As for undeads - will this race leave after death corpses? Which types? If no corpses than undeads will be weaker to them.

On small maps elves will be such a pain for this race. Cheap and pretty powerful archers and your design of race is really weak to elven rush.

So personally i don't like idea of this race. Too many questions and weak points.

General summoning he suggested works different way:
Instead of just gaining instantly ready unit he suggests that summoning will give you unit with 1/x hp that will regenerate some of hp each turn until it will get 100% of his hp.